This is a standard moderation practice we've used for years when people email and ask us to take down a thread. We generally won't take down a thread that has significant comments. At the same time, the people who email in such cases are often feeling distressed, and sending them away with nothing would be mean. That's not how we run HN.
What we usually do is say "We try not to delete posts that got replies, because doing so would be unfair to the other commenters in the thread. However, if you want, we can reopen the thread so you can post your side of the story" (or the relevant information they feel is necessary, etc.—whatever is appropriate to the case).
This is a nice balance between the community's desire to preserve history and eschew censorship, and individuals' need to correct or augment the record. I particularly like that it solves the problem by adding information instead of removing it. It leaves the thread in a better state for readers to make up their own minds.
Most users who we help in this way have nothing to do with YC. It's more general than that: it's how we address the reality that sometimes people change, or feel a need to correct something said about them online, and so on. Surely you can empathize with that? If not, I'd be perplexed.
Trying to stir up a drama about this, as you've done here and at https://news.ycombinator.com/item?id=44207198 (while hiding behind an anonymity cloak, unlike the person you're going after), feels a bit strange. To me this is one of the kinder things we do, while preserving the values of the community.
I wouldn't want to suffer forever over something I'd posted on the internet years earlier, and I doubt you would either. If you have a better solution for cases like this, I'd love to know what it is.
https://news.ycombinator.com/item?id=44246859
FWIW, when potentially live saving content gets flagged on HN, effectively censoring it, I can't help but think there's a concerted effort by some actors (terrorist organizations, 3-letter agencies, foreign countries) to suppress information.
It's a big reason I avoid HN. I can imagine censoring free-speech being HN's downfall.
You laughing your ass off triggers alarms.